Compression-rheostat.



,E. LQCLARK. COMPRESSION RHEOSTATQ APPLICATION FILED H'AY I9. ms.

1,222,182, Patented Apr. 10, 1917.

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,NVENTOR WITNESS EMBHEUN L. CLHHK TTORNE Y E. L. CLARK. comraessldu RHEOSTAT.

APPLICATION FILED MAY 19. l9l5.

Patented Apr. 10, 191 7.

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W W W RK Y mm E N m MC m mL M m WITNESS E. L. CLARK. I COMPRESSION RHEOSTAT.

APPLICATION FILED MAY I9. I915.

1 ,222, 182. Patented Apr. 10, 1917.

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INVENTOR. EMEHEUN L. CLARK A TTORNE Y WITNESS oivirnn STATES PATENT OFFICE.

EMERSON L. CLARK, OF LAKEWOOD, OHIO, ASSIGNOR TO NATIONAL CARBON COMPANY, A. CORPORATION OF NEW JERSEY.

COMPRESSION-RHEOSTAT.

Specification of Lett ers Patent.

Patented Apr. 10, 1917.

Original application filed May 31, 1912, Serial No. 700,558. Divided and this application filed May 19, 1915.

' Serial No. 29,051.

To all whom may concern.

lie it known that I, Emerson L. CLARK, a citizen of the United States, residing at Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful improvement in Compressionl'lheostats, of which the following is a full, clear, and exact description.

'1 his application is a division of my application Serial No. 700,558, filed May 31, 1912, patented June 22, 1915, No. 1,143,810.

T his invention relates to rheostats of the compression type in which the resistor elements consist of carbon, graphite or mixtures of these substances with other materials. However, the invention is not limited to the use of any specific materials, and hence may embrace resistors composed of any materials.

@ne object of my invention is to construct a rheostat with readily replaceable resistor units each having means rigidly attached thereto for radiating the heat.

Angther object is to construct a rheostat with slight frictional resistance movement so that the elements when compressed, or released from pressure, will all move in unison.

Other objects will appear in the appended description.

Referring to the figures:

Figure 1 is an end view of a resistor element.

Fig. 2 is a plan view of the element shown in Fig. 1.

Fig. 3 is a plan View of the radiating plate before the carbon or composition blocks are attached thereto.

Fig. 4 is a sectional view of the radiating plate taken on the line A-A of Fig. 3.

Fig. 5 is a sectional view of the radiating plate taken on the line BB of Fig. 3.

Fig. 6 is a sectional view of the resistor element and radiating plate taken on the line CC of Fig. 2.

Fig. 7 is a. sectional view of a modification showing a resistor element having only one composition block.

Fig. 8 is a plan view of another modification in which the composition blocks are arranged at one side of the radiating plate.

Fig. 9 is an end view of another modifier tion.

Fig. 10 is a plan view of the resistor element shown in Fig. 9.

shown in Fig. 6.

.Fig. 11 is a sectional view of the resistor element taken on the line D-D of Fig. 10.

Fig. 12 is a plan view of the radiating plate shown in Figs. 9, 10 and 11.

Fig. 13 is a modification similar to that shown in Figs. 9, 10, and 11 in which a gauze radiating plate is used.

Fig. 14 is a sectional view of the resistor element taken on the line EE of Fig. 13.

Fig. 15 is a modification in which the com ppsition blocks are cemented to the radiating p ate. I

Fig. 16 is a modification in which the radiating plate is cast in grooves in the composition blocks.

Fig. 17 is an isometric view of the composition blocks of Fig. 16 before the plate is cast therein.

Fig. 18 is an end view of the modification shown in Fig. 17 with the grooves arranged parallel.

Fig. 19 is a modification showing a resistor consisting of one block with a radiating plate cast in grooves therein.

Fig. 20 is a side elevation of the rheostat in which the resistor elements are used.

Fig. 21 is a plan view of the rheostat shown in Fig. 20.

Fig. 22 is an elevation of the end plates of the rheostat shown in Figs. 20 and-21.

Fig. 23 is a modification of Figs. 20 and 21 in which the resistor element is suspended on parallel bars.

Fig. 24 is a partial sectional view of the point of support of the screw rod against the end plate.

Fig. 25 is a partial sectional view of another modification for communicating pressure. Y

Fig. 26 is a plan view of a modification of the rheostat shown in Figs. 20 and 21.

Referring to Figs. 3, 4 and 5, lugs '1 are punched in a plate 3 so as to extend on one side thereof. These alternate with lugs 2 punched so as to extend on the other side of the plate. Composition blocks 4 are then placed between the lugs, one on each side of the plate. The lugs are then firmly pressed against or into the composition blocks as is This arrangement provides for a very rigid resistor having a radiating plate in good contact with the sides of the composition blocks.

In order to prevent the metal from oxidiztill) till ing and producing an undesirable resistance at the contact surface, the metal plate is coated with some metal that will not oxidize readily under the heat to which the element will be subjected in practice. The plate is preferably coated with nickel, though cop per or other metal may be used.

In Fig. 7 a modification is shown in which lugs 1 are punched only on one side of theof various shapes and sizes and the arrangement of the holes may befvaried as desired.

The plate and composition material properly mixed with a suitable binder are placed in a-mold and put under hydraulic or other pressure which forces the material in intimatecontact with the parts of the radiating plate as is shown in Fig. 11.

111 Fig. 13 the radiating plate 3 is displaced by the gauze plate 6. The material forming the block 1 is pressed around the wires in the gauze plate in the samemanner as has been described in the modification in Figs. 10, 11 and 12. The cross section of this type of resistor element is shown in.

Tn Fig. 15 the composition blocks are either brazed or cemented to the radiating plate 3. The brazing material or conducting cement is shown at 41' the thickness being exaggerated somewhat to make the construction clear. FVhen the blocks are to be brazed to the plate they are first coated on one side with copper or other metal and then the plating is joined to the plate by brazing in the usual manner. When the blocks are cemented to the plate they need not be coppe r coated. Conducting cements are well known in the art, and as a typical example the following may be given: 100 parts graphite, 410 parts bronze powder and enough glucose or sugar and water to make a stifi' paste. The paste can be applied to either the plate or the resistor and the two parts pressed together in proper relation. They are then baked to a sufiicient temperature to carbonize the glucose or sugar. After baking it will be found that the cement is conductive and will firmly join the resistor to the plate. The shape of the blocks In Figs. 16 and 19 the composition blocks 4 have undercut corrugations or grooves 7 extending across one side. The blocks are placed in a proper mold with the grooved surfaces in contact or. closely adjacent and with the grooves of the one block running approximately at right angles to .those of the other, and molten metal is poured in so that it will entirely fill all the grooves in the plate and form a radiating plate '9 as shown in Fig. 16. The mold, of course, will be arranged in well known ways so that this plate can be cast. It is obvious that the plates shown in Figs. 16 and 19, as well as those in the other figures, may be square, circular 01' any other shape.

The blocks need not be necessarily arranged with the grooves at right angles.

metal or alloy. The material may be cast in the blocks by pressure casting in a manner well known in the art.

In Fig. 19 a resistor is shown consisting of only one block with undercut grooves and a radiatingplate cast therewith.

Referring to Fig. 20, a rheostat is shown in which the resistor elements are used. End plates 10 and 11 are joined by'four rods 12 passing through holes 14: in the end plates (Fig. 22) and properly fastened by the nuts 13. The shape of the plates and the arrangement of the holes is shown in 22. Tu the center a plate 14:, somewhat similar to plates 10 and 11, is fastened rigidly to the rods 12 by screws 15 or by 'other appropriate means. Tnsulated rods 16 pass loosely through loosely through the hole 22 in the plate 10. I

The pin 23 is fastened to the bar 19 and extends loosely through a hole in the plate 11. The resistor elements can be readily inserted or removed so that a defective one can be replaced without trouble.

The type of resistor elements in Figs. 20 and 21 is similar to that shown in Fig. 8, in which the composition blocks are secured at or near the top of the radiating plate. The blocks may be secured in any of the ways disclosed herein. Each resistor element is supported onthe lower rods 12 by means of its radiating plate as shown in dotted lines in Fig. 22.

End plates 24, 25 are placed at each end ofthe rheostat. These plates must be rigid enough to transmit the pressure uniformly over the siyfaoe of the composition biocks when epplietl through the screw and pin 23. The end plates are preferably larger than resistor blocks, so as to have additional for radiating heat as shown in the The encl plates are supported by the lower rods 12 in the same manner as are the sesistor elements.

he lower parts, of the end plates and of the radiating plates of the resistor elements peiinit condnctois to he clamped thereto nce elements may arranged in oups if, clesirecle As shown in c terminais 26 anti 2'? are clampe i pistes 24 end so that ail of the iii! 6 .i LTGER rt circuited the reels 12 and 16 may 1 covered with transits tubingor I ctiacal insulating and heat inial 3;. 4: shown H1 section at it unelerstcoti mngs and Washers vvili are joined to the one I 1. s indicated in 21 by the shown in soiiel 0 holes 22 in the end plates 19 encl 1 be properly insulated by hoshings shown in Fig. 2. The insnie'tion sit is only one We; 5 in w circuit may he prevented 1 a 3 o piovio hence iii press a point or'heli contac' f the i s X rotetivc W will cause the pl miss and produce on fluctuations in the resistance of the 25 another arrangement is shown Whciehy ti e end plate is not cases to move sidetvise. Sockets t rmed the mete end the 20 contain it 1 i which may have a retainer to "prevent from dropping out.

The rheostat shown in is essen tially the sense as that of Figs. 20 and 1 hut sicie pieces 32 made of insulating lteriel such as ti ansite to? e:2eni;J; These members are fastened on hoth sides of enci members 10 and 11 to inclose iii the blocks four sides whereby e ch I or iilitfi2 is produced when 1 become hy the current T18 hale 2'5 and 27 3 6 5121 i'atiisti 1/ g sli ing tne cools stat against the metal plate 2.42 If the oile is compressed from one side only so that it would he, say inch shorter than it originally Was, the first hiock on the noviig end of the vile would move inch, and t ie succeeding locks would move progressively less distances. If the pile is compressed from both ends as in epplicants case e two outside blocks would move only 1; inch and the succeeding ones progressively less. Hence to obtain the some resistance the average distance of movement of the blocks in one type is twice that of the other. In order to obtain gracluai ancl uniform variation of resistance the movement must be uniformly transmitted through the entire pile. It is evident, therefore, that the changes of resistance should he ooteinei cs movement of the blocks 5" 1 (no w, ."s 4. a so, piovice ior such iemiceo $1 1 e compiessee '4 no. site it A e t the ins' movements 0 the own set W last blocks Wi l furnish a near the naitliile the by the pistes would prevent the dily, and the varihe irregular, espe-v y at ni mum resist; e.

conzse e ieced at the wiii he movement i of sci" iegligibi- (2 anti when is coco: at the bottom.

s e certain amount consisting of iron, a

then supported on the upper bearing rods 12" bon adjacent to the surface of the plate and fastened eccentrically thereto.

2. In electric rheostats, a radiating plate having punchedlugsrextending from both sides thereof and a resistance block held in place on' each sideof said plate by said lugs.

3; In electric rheostats, a radiating plate having punched lugs and a block of resistance material retained in place by said lugs. 4:. In electric rheostats, a radiatin plate coating of di cultly ox'idizable metal thereon and a block of resistance material rigidly fastened to the plate.

5. In an electric rheostat, the combination of end plates, connecting means joining said plates, resistance blocks, radiating plates rigidly fastened to said blocks, said blocks and lates resting and pivoting on certain of" said means, and means for forcing the,

signature.

blocks into contact.

6. In an electric rheostat, a plurality of independently a movable resistors, each renaaaiea sister consisting of resistance material secured to a radiating plate, means extending lengthwise of the rheostat for supporting 8. In an electric rheostat, the combination of end plates and side plates to form an'in closure, resistance blocks, radiating plates rigidly fastened to said blocks, means for pivotally supporting the blocks and plates within the inclosure and means for cornpressing the blocks.v v

9. In an electric rheostat, the combination of end plates and side plates to form an inclosure, resistance blocks mounted on radiating plates, means for pivotally supporting the blocks and plates, means for dividing said inclosure into two compartments vand a member for simultaneously compressing the blocksv in both compartments.

In testimony whereof, I hereunto aiiin my EMERSON In CLARK. 

